1. Field of the Invention
This invention relates, in general, to hopper closure devices, and in particular, to self-cleaning devices.
2. Description of the Prior Art
Vehicles having hopper beds are widely used for transporting bulk materials, such as grain, because of the ease and efficiency of unloading. Most of the hoppers are of the type having a bottom gate or door which is conventionally opened and closed by means of a rack and pinion assembly. Because of its location, the door bears a large proportion of the weight of overlying material and therefore it is highly desirable to reduce the friction of the opening and closing mechanism as much as possible. In opening the hopper door, the friction between the door and overlying material must be overcome. A frequent problem associated with hopper doors is the caking and freezing of water mixed with dirt, grain, and other material in the rack and pinion assembly causing a jamming of the door. Freeing the door can be time consuming and expensive and may result in structural damage to the discharge assembly.
In attempting to solve this recurring problem, various devices have been invented, generally to prevent build-up of material on the rack and pinion assembly. Typical of such inventions are those disclosed in U.S. Pat. No. 2,989,931 issued to R. W. Joy; U.S. Pat. No. 3,085,517 issued to J. T. Smith; and U.S. Pat. No. 3,983,861 issued to J. H. Bagwell. Such systems, while representing an advance in the art, have only been partially effective in preventing build-up of form material and "freezing" of the hopper doors. Jamming of hopper doors is therefore still a common problem.